Battery

Abstract

The battery comprises a battery main body provided with a pair of positive and negative terminals, a pair of external positive and negative terminals for connecting the pair of positive and negative terminals to an external apparatus, and a protective element provided interposed between the terminals and the external terminals, wherein the protective element is composed of a passive element alone and comprises a thermal cut-off. Further, the resistance R across the pair of external terminals is predetermined to be always greater than V t /I t . In this arrangement, in the case of a weak external shortcircuiting causing no battery performance deterioration, burst and ignition, the thermal cut-off can be prevented from blowing to impair the battery performance. Since proper protection of the battery is realized by the use of an inexpensive passive element alone, the production cost of the battery can be reduced.

What is claimed is:  
     
         1 . A battery comprising: 
 a battery main body provided with a pair of positive and negative terminals;    a pair of external positive and negative terminals for connecting the pair of positive and negative terminals to an external apparatus; and    a protective element provided interposed between the terminals and the external terminals, wherein the protective element is a passive element which comprises a thermal cut-off.    
     
     
         2 . The battery described in  claim 1 , wherein as the protective element there is used a thermal cut-off.  
     
     
         3 . The battery described in  claim 1  or  2 , wherein the resistance R across the pair of external terminals is represented by the following relationship: 
       
         R>V 
         t 
         /I 
         t 
       
       wherein V t  represents the voltage across the external terminals developed when time t elapses from the beginning of discharge of the battery upon shortcircuiting; and I t  represents the fusion current of thermal cut-off corresponding to time t.